text: Group 4 metallocenes also catalyze dehydrogenation of ABs.  Activity is affected by metal (Ti > Zr > Hf) and inhibited by bulk. Unlike other catalytic processes, the reaction proceeds via a linear aminoborane [NRBH], which then cyclodimerizes through a dehydrocoupling process on the metal. Most of the zirconocene complexes contain the zirconium in the +4 oxidation state, and the systems are not very active catalysts for amine-borane dehydrogenation. In contrast to these systems, the cationic zirconocene complex [CpZrOCHP(Bu)] effectively catalyzes the reaction, with the most notable example being the dehydrogenation of dimethylamineborane in 10min at room temperature.